Hamilton fastest amid Mercedes warnings to rivals

Monza: Lewis Hamilton sped ahead in Friday's free practice for the Formula One Italian Grand Prix as his Mercedes team warned it was ready to drop Hamilton or Nico Rosberg if they do not restrain their rivalry.

The battle between the Mercedes drivers, particularly after Rosberg admitted he was to blame for a crash between the two, has dominated the Formula One world championship.

"We have made it very clear this is an unacceptable scenario for us, actually for both of them," Mercedes team boss Toto Wolff told BBC radio.

"We don't want this to happen ever again and the consequences are very easy. If we are not able to manage the two of them following the Mercedes Benz racing spirit then we need to admit that and take decisions and take consequences of having a different line-up probably," Wolff added.

Hamilton, who is 29 points adrift of Rosberg in the title race, was six-tenths of a second clear of McLaren's Jenson Button in the opening free practice, in a clear demonstration of his intent to make up lost ground.

Rosberg was third fastest ahead of two time champion Spaniard Fernando Alonso of Ferrari, Dane Kevin Magnussen in the second McLaren and defending champion Sebastian Vettel in the leading Red Bull.

Vettel's teammate Australian Daniel Ricciardo, winner of three of the last six races, only completed 12 laps before retiring with an engine problem.

Hamilton said on Thursday he was uncertain about how hard he can race to beat Rosberg following their clash at the Belgian Grand Prix two weeks ago.

The Briton said the decision of the International Automobile Federation (FIA) not to punish Rosberg had left him uncertain as to how hard they, and other drivers, can race against each other.